HEAT-RESISTANT POLYIMIDE BLENDS AND LAMINATES

Abstract: This invention relates to heat-resistant polyimide blends and molded parts thereof, which have excellent heat and moisture resistance, are relatively soluble in organic solvents, have excellent mechanical processibility, and are suited for laminating and molding. The blends contain a thermoplastic polyimide component and a thermosetting imide oligomer. The weight ratio of the thermoplastic component to thermosetting component is selected in the range of 99/1 to 5/95. The thermoplastic polyimide component has a number average molecular weight of 10,000 or more.

Description: Heat-Resistant Polyimide Blends and Laminates Technical Field The invention described herein pertains generally to novel heat-resistant polyimide blends which have excellent heat and moisture-resistance, are soluble in organic solvents, have excellent mechanical processibility, and are suited for laminating and molding. Additionally, the present invention relates to: new laminates made from blends of thermoplastic polyimides and thermosetting imide oligomers having improved thermal stability, high T g , and improved thermoplastic properties; and new high strength, low cost, fracture resistant, reinforced polyimide composites and laminates made from said blends where the composite is reinforced by fibrous materials such as carbon fibers, glass fibers, or Kevlar® and processes for their manufacture. Background of the Invention Polyimides are useful as components which require excellent thermal, electrical and/or mechanical properties. For general discussion of polyimides preparation, characterization and applications see Polyimides, Synthesis, Characterization and Applications, K. L. Mittal, ed Plenum, NY 1984. Polyimides based on pyromellitic dianhydride and various organic diamines are disclosed in U.S. Patent 4,485,140 to Gannett et al (E.I. DuPont de Nemours and Co.). Polyimides based on diamines such as 2,2'-di-( -aminophenyloxy)diphenyl and various dianhydrides are disclosed in U.S. Patent 4,239,880 to Darms (Ciba-Geigy Corp.). Harris et al. in U.S. Patent Application 07/315,327, has disclosed the preparation of soluble polyimides based on polyphenylated dianhydrides. The polyimides taught in this reference are typically rod like polyimides and possess little if any thermoplastic properties. In U.S. Patents 4,271,288, 4,239,694 and 4,421,929, Woo (DOW Chemical Co.) teaches the use of certain tetracarboxylic acids as condensation monomers with diamines including oxyalkylene and alkylenedioxy diamines. However, none of these diamines have geminal alkyl groups beta to the carbon atom bearing the aromatic amino end group. Numerous patents deal with the manufacture of composites utilizing carbon fibers or other similar fibrous reinforcing agent with polyimides. In U.S. Patent 4,851,280, Gupta teaches the use of carbon fiber reinforced polyimide composites for fabricating tools. Gupta teaches the use of a different class of polyimides than those employed in the present invention. In U.S. Patent 4,395,514, Edelman teaches a process for the preparation of polyimide composites including carbon fiber reinforced polyimide composites. The main thrust of the Edelman patent is the use of a class of cyclic peroxymetal catalysts. Edelman teaches the use of divalent aryl radicals. Recently, with advances in electric circuitry, copper-clad laminates have been used in new ways and required to have superior characteristics. Particularly, an increase in wiring density has been required, leading to lamination of wiring boards and also to size reduction of the through holes. In these circumstances, there is a demand for copper-clad laminates, which are processible under mild conditions, and less subject to smear generation during drilling. Meanwhile, there are also demands for productivity improvement and cost reduction dictating more and more stringent processing conditions in actually mounting wiring boards, particularly in connection with the hot air leveler or reflow soldering. Key requirements are superior heat resistance and moisture resistance of the copper-clad laminates as substrates than heretofore obtainable. To meet these demands, there is a trend for utilizing additionally hardened polyimide resins in lieu of epoxy resins, which have been finding extensive applications for copper-clad laminates. It is well known in the art that polyimide resins, when utilized for copper-clad lamination, are advantageous in that substantially no smear is generated during drill processing and that their heat resistance during processing is improved. However, the prior art hardened polyimide resins have posed the following problems. For example, while Kerimid™ resins, which are primarily composed of a combination of bismaleimide and 4,4'-diaminodiphenyl methane, have excellent lamination characteristics, 4,4'-diaminodiphenyl methane used in the synthesis is highly reactive, thus posing a shelf-life problem. The varnish and prepreg using it can be used for only a short period of time. Additionally, 4,4'-diaminodiphenyl methane is toxic to the human body. Kerimid processing requires heating at high temperatures for long periods of time, which is a significant disadvantage. Further, those resins which are obtainable from bismaleimides and diamines, are inferior in their moisture resistance. Therefore, preservation of the obtained laminates has traditionally required detailed attention to moisture absorption. In order to solve the above problems inherent in polyimide, many improvements have been proposed, particularly various polyester imide resins, such as those described in U.S. 4,757,118, U.S. 4,362,861, and U.S. 3,852,246, and Japanese Patent Application Laid-Open No. 1-123819. Those resins which are obtainable by reacting N,N'-bisimide of unsaturated dicarboxylic acids and aminoethyl benzoate, although suitable for laminates, are inferior in their solubility in low-boiling solvents and pose problems in their coating on glass cloth or fiber or the like when producing prepregs. Further, their solutions must be preserved with care. Further, the polyester imides produced are usually lower in thermal softening points, than the polyimide alone, and additionally are inferior in their heat resistance when compared to the polyimide. The polyester imides do however, have good fluidity. Materials such as "LaRC-TPI", available from Hiromichi Ota, and "New-TPI" available from Mitsui Toatsu, have also been reported as polyimide resins capable of being processed by fusion techniques and injection molding respectively. Recently, a "semi-IPN" has been introduced into the field of polyimides in order to attain further improvement in the heat resistance and toughness of the polymer as indicated in U.S. 4,695,610. None of the above composite patents teach or insinuate that the polyimides or polyimide composites of the present invention would have the unusual properties necessary. Brief Description of the Drawinεs Fig. 1 illustrates a prepreg drying cycle showing a heating ramp under vacuum followed by a one hour hold time at 250°C followed by a rapid cooling ramp still under vacuum. Fig. 2 illustrates a compression molding cycle showing a heating ramp at 27min. to 300°C, a 25 minute hold under pressure, a second heating ramp at 17min., an hour hold still under pressure, followed by a 27min. cooling ramp under pressure to a temperature below 65°C. Fig. 3 illustrates the conditions for the preparation of a cast plate showing a heating ramp to 520°F, followed by a hold for 25 min, additional heating to 580°F, followed by a hold for an additional hour, with a rapid cooling ramp. Fig. 4 illustrates the glass transition point (T g ) as a function of the weight percent of added thermid. Fig. 5 illustrates the flexural strength as a function of the weight percent of added thermid. Fig. 6 illustrates the flexural modulus as a function of the weight percent of added thermid. Fig. 7 illustrates the fracture energy (G lc ) as a function of the weight percent of added thermid. Summary of the Invention We have discovered that a desirable new class of polyimide compositions which have excellent heat and moisture resistance, are soluble in organic solvents, have good mechanical processing properties and are suitable for laminating and molding. These properties will make the polyimides and polyimide components ideally suited for use in the production of high performance compositions. An object of this invention is to provide novel polyimide blends of thermoplastic polyimides and thermosetting imide oligomers. It is a further object of this invention to provide novel polyimide blends of thermoplastic polyimides and thermosetting imide oligomers which can be coated on a reinforcement material. A further aspect of this invention is to provide a method of manufacturing the heat-resistant laminate by independently dissolving a thermoplastic polyimide and a thermosetting imide oligomer in an aprotic solvent, subsequently blending the two solutions to obtain a homogeneous blend solution, and precipitating the blend solution thereby obtaining the polyimide blend composition which can then be coated and impregnated on a reinforcement material. Detailed Description of the Invention The novel heat-resistant laminate blend material according to the invention comprises, as essential components: (1) a thermoplastic polyimide represented by the structure as shown in formula (I), where Z is a tetravalent organic radical selected from the group consisting of a carbocyclic aromatic containing radical and a heterocyclic aromatic containing radical where each anhydride group is located on an aromatic ring with the carbonyl units in an ortho orientation relative to one another, and where Q is divalent organic radical selected independently from the group consisting of a carbocyclic aliphatic radical, a carbocyclic aromatic containing radical, and a heterocyclic containing radical, wherein the term carbocyclic aromatic containing radical and heterocyclic aromatic containing radical used to define Z, is meant to include any radical which has the anhydride groups attached to one or more aromatic ring(s) and when describing Q has the amine groups attached to one or more aromatic ring(s), and wherein while the rings are usually unsubstituted, they may be substituted, particularly with halogens; and (2) a thermosetting imide oligomer represented by formula (II), representative examples of which are commercially available in the United States as Thermid®-series from National Starch Co., and in Japan from Kanebo, NSC Co., Ltd.. wherein Q and Z have the values previously defined, the groups Z being either the same or different, n being a positive integer of from 1 to 30, and X is a form of trivalent bond shown attached to group Z, which occupies two of the bonds, thereby leaving one additional bond for subsequent bonding to other components of the oligomer, and selected from the chemical formula group consisting of (Ilia) (IHb) (IIIC) The thermoplastic polyimide represented by formula (I) represents the polycondensation reaction of at least one dianhydride of formula (IN) and one diamine of formula (V) (V) H 2 Ν-Q-ΝH 2 wherein Z and Q are as previously defined. In preparing the above polyimides, a diamine of formula (N) is reacted with a dianhydride of formula (IN) or ester derivatives of the dianhydride of formula (IN). The combined molar amounts of the diamine and dianhydride or dianhydride derivative, should be close to a one to one molar mixture. However, 10% excess of either component is acceptable. Once the polymerization has been completed, the last component to react will determine the polymer end group. The polymer end groups can, thus, be an amino group, an anhydride group or a mixture thereof. Alternately, a chain termination or limiting reagent can be added to the polymerization mixture to force termination of a growing polymer chain. Such chain termination or limiting reagents are used to limit the molecular weight of the polymer and are well known in the art. Amine termination reagents commonly employed include aniline or substituted anilines. Common carboxy terminating reagents include phthalic anhydride and other similar aromatic anhydrides. Without being limited to the following list, in that the examples are for purposes of illustrating members of the type of dianhydrides of formula (IN) are selected from the representative and illustrative group consisting of: pyromellitic acid dianhydride, 3,6-diphenylpyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 2,3,3 ',4'-benzophenonetetracarboxylic acid dianhydride, 2,2',3,3 '-benzophenonetetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(2,5,6-trifluoro-3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl) ether dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, Ν,Ν-(3,4-dicarboxyphenyl)-Ν-methylamine dianhydride, bis(3 ,4-dicarboxyphenyl)diethylsilane dianhydride, 2,2-bis(3 ,4-dicarboxyphenyl)- 1,1,1,3,3,3 -hexafluoropropane dianhydride, 4,4'-[4,4'-isopropylidene-di(p-phenyleneoxy)]bis(phthalic anhydride) which is derived from the General Electric bis-phenol A™, 2,3,6,7- and 1,2,5,6-naphthalene-tetracarboxylic acid dianhydride, 2,6-dichloronaphthalene-l,4,5,8-tetracarboxylic acid dianhydride, thiophene-2,3,4,5-tetracarboxylic acid dianhydride, pyrazine-2,3,5,6-tetracarboxylic acid dianhydride and pyridine-2,3,5,6-tetracarboxylic acid dianhydride as well as esters of the above listed compounds. Without being limited to the following list, in that the examples are for purposes of illustrating members of the diamine of formula (N) include: 2,6-diaminopyridine, 2,5-diaminopyridine, 2,4-diamino-6-hydroxypyrimidine, 2,4-diaminopyrimidine, 3,5-diamino-l ,2,4-triazole, 4-chloro-2,6-diaminopyrimidine, 2,4-diamino-s-triazine, 2-chloro-4,6-diaminotriazine, 6,6'-diamino-2,2 '-bipyridine, 1,4- diaminobenzene, 1,3-diaminobenzene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, l,3-bis(3-aminophenoxy)benzene, 1.3 -bis(4-aminophenoxy)benzene, 1 ,4-bis(3 -aminophenoxy)benzene, 1 ,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)-l,l '-biphenyl, 4,4'-bis(3-aminophenoxy)-l,l '-biphenyl, 2,2'-bis(trifluoromethyl)-4,4 '-diamino-1,1 '- biphenyl, l,3-bis(4-aminophenoxy)-2,2-dimethylpropane, 1 ,3-bis(4-aminophenoxy)-2,2-diethylpropane, 1 ,2-bis(3-aminophenoxy)ethane, l,2-bis(4-aminophenoxy)ethane, bis[2-(4-aminophenoxy)ethyl]ether, bis[2-(3-aminophenoxy)ethyl]ether, bis{2-[2-(4-aminophenoxy)ethoxy]ethyl}ether, 1 ,2- bis[2-(4-aminophenoxy)ethoxy]ethane, 1 ,3-bis(4-aminophenoxy-4 '-benzoyl)benzene, l,4-bis(4-aminophenoxy-4 '-benzoyl)benzene, 4.4 '-bis(4-aminophenoxy-4 '-benzoyl)benzophenone, 4,4'-bis(4-aminophenoxy-4 '-benzoyl)diphenylether, and l,4-bis(4-aminophenoxy)-2-phenylbenzene. In a preferred embodiment of this invention, the thermoplastic polyimide will have generic formula (NI), where, R 1 and R 2 are selected from the group consisting of hydrogen, aliphatic and aromatic groups from 1 to 18 carbons, and halogenated aliphatics and aromatics from 1 to 18 carbons, Ar 1 is a divalent organic aromatic group where the ether linkage and amine linkage are in a para arrangement, and Z is as defined previously. The method of manufacturing the novel polyimide blend composition comprises the steps of: (1) independently dissolving the thermoplastic polyimide represented by formula (I), and the thermosetting imide oligomer represented by formula (II) in an organic solvent; (2) blending together the two separate solutions into a homogeneous blend solution; and (3) precipitating the polyimide blend composition in a coagulating solvent. The weight ratio of component (I) / component (II) is selected in a range of 99:1 to 5:95. The thermoplastic polyimide (I) has a number-average molecular weight of 10,000 or above. The polyimide blend resins obtained are particularly good in bonding to other substrates and in their flexibility. In addition, moldings produced from these resins are less prone to the generation of voids and cracks. Thus, the resins are useful in flexible printed circuit boards and electric materials requiring excellent properties. In order to obtain a homogeneous blend composition, the solution of thermoplastic polyimide and thermosetting imide oligomer are stirred at from about 25- 150°C , preferably from about 50-120°C; for 2-24 hours, preferably 4-24 hours. The homogeneous blend solution is typically coagulated by dropping the solution into an alcoholic solvent (e.g., methanol, ethanol, isopropanol, etc., or any solvent capable of producing the precipitate of the blend composition). The coagulating solvent can even be water. The obtained precipitate of the blend composition is filtered and collected. Typically, the collected filtrate is solvent-exchanged with methanol or the like using a Soxhlet extractor to facilitate the subsequent drying under reduced pressure. The resulting final blend product is a powder. Effective organic solvents for the reaction leading to the formation of the blend composition are polar aprotic organic solvents which include: sulfoxide solvents, e.g., dimethyl sulfoxide, diethyl sulfoxide, etc.; formamide solvents, e.g., N,N'- dimethylformamide (DMF), N,N'-diethylformamide, etc.; acetamide solvents, e.g., N,N'-dimethylacetamide (DMAc), N,N' -diethylacetamide, etc.; N-methylpyrrolidinone (NMP); and phenol solvents, e.g., o-cresol, -cresol, p-cτeso\, 4-t-butylphenol, etc. These solvents can be used alone or as a mixture of two or more solvents. Furthermore, these polar solvents may be used in mixtures with polyimide non- solvents, e.g., methanol, ethanol, isopropanol, benzenemethylcellosolve, etc. One method of manufacturing a novel thermoplastic polyimide of formula (VI) comprises dissolving an organic diamine represented by formula (Nil) where, R 1 and R 2 are as previously defined, the groups R 1 and R 2 being the same or different, in an inert gas atmosphere (e.g. argon, nitrogen, etc.), and an organic tetracarboxylic acid moiety or derivative thereof of chemical formula represented by formula (HI) where Z is as previously defined in a polar aprotic solvent such as DMF, DMAc or ΝMP, or a phenolic solvent such as m-cresol. A viscous polyamic acid solution is obtained. The reaction temperature is from about -15 to 120°C, preferably -15 to 100°C, and more preferably, -5 to 50°C. The reaction time is from about 1-5 hours. To thermally imidize and dehydrate the polyamic acid, an azeotriping agent may be added and the polyamic acid is converted into a polyimide under refluxing azeotropic conditions. The azeotroping agent may be xylene, toluene, and similar aromatic hydrocarbons, and more preferredly, is toluene. In the reaction, azeotropic water is removed using a Dean-Stark trap. Thermal imidization may also be carried out without an azeotroping agent in a refluxing solvent, which optionally contains isoquinoline. The polyimide solution is subsequently poured into water or an alcoholic solvent while vigorously stirring the system to effect the precipitation of the polyimide polymer as a powder. The powder is filtered, preferably solvent-exchanged with methanol using a Soxhlet extractor to facilitate the drying. The drying is completed under reduced pressure to obtain the thermoplastic polyimide powder. While in the above example, the conversion of the polyamic acid into the polyimide was attained by thermal imidization and dehydration, this is by no means limiting the reaction to such means, and other synthetic means to effect the polyamic acid to polyimide conversion are contemplated within the scope of this invention. For example, a dehydrating imidizing agent, with or without a catalyst could be added to the polar organic solvent solution containing the polyamic acid for a chemical dehydration and imidization of the polyamic acid. This process may be effected by heating as well. Examples of the dehydrating imidization agent are organic carboxylic acid anhydrides, N,N'-dialkyl carbodiimide, lower fatty acid halides, lower halo-fatty acid anhydrides, alkylsulfonic acid dihalides and thionyl halides as well as mixtures of these compounds. Acetic acid anhydride is a preferred embodiment. Other preferred reagents would include ketene and benzoic acid anhydride. Examples of the catalysts which may be used to assist the reaction would include pyridine, quinoline and tertiary amines. Specifically, 3,4-lutidine, 3,5-lutidine, 4-methylpyridine, 4-isopropylpyridine, N-dimethylbenzylamine, 4-benzylpyridine and 4-dimethyldodecylamine. The number-average degree of polymerization (DP; P.J. Flory, Principles of Polymer Chemistry: Cornell University Press: Ithaca, NY, p. 91, 1953) of the thermosetting imide oligomer, one of the constituent components according to the invention, is suitably 1 to 30, preferably 1 to 15, more preferably 1 to 10. If the degree of polymerization is excessive, the solubility in organic solvents is reduced. If the degree of polymerization is insufficient, on the other hand, problems are posed in connection with the mechanical strength. As for the thermoplastic polyimide as the other constituent component according to the invention, the molecular weight is not particularly limited. However, in order to maintain the mechanical strength of the product polyimide resin, the number-average molecular weight is suitably 10,000 or above, preferably 20,000 or above, more preferably 30,000 or above, particularly preferably 40,000 or above. It is often difficult to directly measure the molecular weight of polyimide polymers. In such cases, the measurement is made indirectly by estimation. For example, where a polyimide copolymer is synthesized from polyamic acid, a value corresponding to the molecular weight of the polyamic acid may be thought to be the molecular weight of polyimide. The dianhydride component comprises, as its essential component, an organic dianhydride represented by formula (IV), but it is possible to copolymerize with a dianhydride wherein Z in formula (IN) is replaced by Z', but being selected however, from the same Markush group as that previously designated for Z. In an analogous manner, it is possible to copolymerization with a diamine of formula (N) using the substitution of Q' for Q, but being selected from within the same Markush grouping. Once again, without being limited to such, examples representative of the Markush groups Z and Z' would include: Ouϋπc. tx xAXrxx -s- XrXrxx These organic tetracarboxylic acid dianhydrides may be used alone, or in combinations of two or more of them. Further, for illustrative purposes only, representative examples of the organic diamino compounds as represented by formula (V), (V) H 2 N-Q'-NH 2 which are capable of copolymerizing with the thermoplastic polyimide represented by formula (I), and wherein Q' in the organic diamine compound represented by formula (N) may be any divalent organic group described previously, and most preferably, contains at least one aromatic group. Without being limited to such, specific examples of Q and Q'are: orτπrτπ) [orπoi CF,σ iQ » 3QΦ CH, These exemplified groups can be used alone or in combinations of two or more of them. As noted above, the novel polyimide blend composition has particularly high heat-resistance and excellent mechanical properties. Without being held to any particular theory, it is thought that these properties are attributable not only to the attainment of a simple polymer blend or semi-IPN structure (i.e., mutually introducing polymer mesh structure), but rather due to the effective contribution of the blend composition as a polymer alloy system. This speculation is inferred from the fact that the composition has a peak maxima of mechanical properties exceeding those of the sole thermoplastic polyimide or thermosetting imide oligomer, as evidenced by Figures 5 to 7. Further characterization of the polyimide blends produced by the synthetic routes detailed in this invention, indicates that the blends can maintain semi-crystallinity even after the blend composition is produced. Additionally, the melt viscosity of the blend composition is low. These features potentially lead to the conclusion that either the thermoplastic polyimide or the thermosetting imide oligomer, or the combination of them, has a plasticizer effect. While the composition described comprises as its essential elements, the polyimide resins, it is possible to use in combination, if necessary, well-known epoxy resins, epoxy resin hardening agents, hardening promoters, fillers, incombustible agents, reinforcing agents, surface treatment agents, pigments and various elastomers. A well-known epoxy resin is a compound having two or more epoxy (or glycidyl) groups in its molecule. As an example, it may be at least one member of the group consisting of polyglycidylether compounds derived from divalent and higher valence phenols, e.g., bisphenol A, bisphenol F, hydroquinone, resorcinol, furylglycine, tris-(4-bisphenol F, hydroquinone, resorcinol, furylglycine, tris-(4- hydroxyphenyl)methane, 1,1,2,2-tetrakis (4-hydroxyphenyl)ethane, etc., from tetrabromobisphenol A and other brominated polyphenols, and from novolak and other halo-polyphenols, novolak epoxy resins as products of reaction between phenols, e.g., phenol, o-cresol, etc., and formaldehyde, amine epoxy resins derived from aniline, p - aminophenol, w-aminophenol, 4-amino-metacresol, 6-amino-metacresol, 4,4'- diaminodiphenyl methane, 3,3'-diaminodiphenyl methane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1 ,4-bis(4-aminophenoxy)benzene, 1,4-bis (4- aminophenoxy)benzene, 1,3-bis (3-aminophenoxy)benzene, 2,2-bis(4- aπ_inophenoxyphenyl)propane, /.-phenylene diamine, w-phenylene diamine, 2,4-toluene diamine, 2,6-toluene diamine, -xylene diamine, -xylene diamine, 1 ,4-cyclohexane- bis(methyl amine), l,3-cyclohexane-bis(methyl amine), 5-amino-l-(4 '-aminophenyl)- 1,8,8,-trimethyl indane, 6-amino-l-(4-aminophenyl)-l,8,8-trimethyl indane, etc., glycidyl ester compounds derived from aromatic carboxylic acid, e.g., /? -oxybenzoic acid, terephthalic acid, isophthalic acid, etc., indane epoxy resins derived from 5,5- dimethyl indane etc., and alicyclic epoxy resins, e.g., 2,2-bis(3,4- epoxycyclohexyl)propane, 2,2-bis [4-(2,3-epoxypropyl)cyclohexyl] propane, 2,2-bis[4- (2,3-epoxypropyl)cyclohexyl]propane, vinylcyclohexane dioxide, 3,4-epoxycyclohexane carboxylate, etc., and further triglycidyl isocyanulate and 2,4,6-triglycidoxy-s-triadine, etc. These resins may be used alone or in combinations of two or more of them. Examples of well-known epoxy hardening agents are phenolic hardening agents, e.g., phenol novolak, cresol novolak, etc., and hydrazide compounds. Examples of the hardening promoters are amines, e.g., benzyldimethyl amine, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8-diazabicycloundecene, etc., imidazole compounds, e.g., 2-ethyl-4-methyl imidazole, and boron trifluoride amine complexes. To improve the mechanical strength, well-known elastomers may be effectively added. Examples of the well-known elastomers are: Silastic ATBN ATS x + y =3 n=5, m=l, z = 10 R = -COOH (CTBN, CTB) :OOCH 2 CHCH COCH=CH 2 (VTBN) OH Incombustible agents and inorganic fillers may be suitably added. Inorganic fillers may be used which are water-insoluble and insulating. Examples of such inorganic fillers are metal oxides, such as silica, alumina, zirconia, titanium dioxide and zinc flower, metal hydroxides such as magnesium hydroxide and aluminum hydroxide, natural minerals such as talc, kaolin, mica, waltherite and clay minerals, and insoluble salts such as calcium carbonate, magnesium carbonate, barium sulfate and calcium phosphate. Examples of the reinforcement material are woven fabric, non- woven fabric, mat, paper and combinations of these materials, and continuous fibers such as carbon fibers, glass fibers, aramide fibers, liquid crystal polyester fibers, poly(p-phenylenebenzobisthiazole) (PBT) and poly(p-phenylenebenzobisoxazole) (PBO) fibers, alumina fibers and so forth. These reinforcement materials may be treated with silane coupling agents to enhance adhesion to the blend. The invention will be better understood by reference to the following examples which are included for purposes of illustration and not limitation. The following terms which are used throughout the examples and claims have the following definitions: g - gram(s), mol - mole(s), ml - milliliter, L - liter(s) Example #1 Preparation of l,3-bis(4-nitrophenoxy)-2,2-dimethylpropane To a dried 2,000 ml round bottom flask were attached a N 2 bubbler, a Dimroth reflux condenser and a mechanical stirrer, and the flask was flushed with N 2 . 146.1 g (0.920 mole) of l-nitro-4-chlorobenzene and 45.1 g (0.470 mole) of 2,2- dimethylpropane-l,3-diol were well mixed in a mortar and then added to the flask. The mixture was dissolved in 200 ml of N-N'-dimethylacetamide, and then 400 g (2.820 mole) of anhydrous K 2 CO 3 was added to the solution. The system was stirred under reflux in a N 2 stream for 26 hours. The reaction liquid was added to 2,000 ml of ice water and carefully neutralized with concentrated HCl. The precipitate that formed was then filtered, and recrystallized twice using toluene. The product was then dried under reduced pressure (@ 65°C) to obtain 133.3 g (yield: 82.0%) of the dinitro compound (hereinafter referred to as BNPDMP), the melting point of which was 165-6°C (reported value: 164°C). Spectral data of the obtained BNPDMP were as follows. IR (KBr, cm '1 ): v = 3100, 2950, 1680, 1600, 1500, 1340, 1290, 1170, 1120, 1040, 1000, 860, 770, 680 'H-NMR (acetone- d 6 ): δ = 1.20 (s,6H, -CH 3 ), 4.08 (s, 4H, -CH 2 -0-), 7.19 (m, 4H, aromatic H), 2 nd 8.15 ppm (m 4H, aromatic H) Elemental analysis for C 17 H 18 N 2 : Calculated value (%): C: 58. 74 H: 23.8 Measured value (%): C: 58.56, H: 23.92 Example #2 Preparation of l,3-bis(4-diaminophenoxy)-2,2-dimethylpropane To a dried 2,000 ml round bottom flask were attached a bubbler, a N 2 bubbler, Dimroth reflux condenser, a mechanical stirrer, and a 1 ,000 ml addition funnel containing 600.0 g (12.080 mol) of hydrazine hydrate. To the flask was added 286.44 g (0.841 mol) of BNPDMP, 13.71 g of 5 wt. % Pd-C and 1,000 ml of dry ethanol. The mixture was heated to reflux and hydrazine was added dropwise over a 90 minute period. After the mixture was stirrer and heated at reflux for an additional 4 hours, it was filtered through celite under reduced pressure. The filtrate was reduced to dryness under reduced pressure. The residue was recrystallized using ethanol to obtain 196.8 g (yield: 95.5%) of diamine (hereinafter referred to as BAPDMP), having a melting point of 114 - 5°C (reported value: 113°C). Spectral data of the obtained BAPDMP are as follows. IR (KBr, cm- 1 ): ξ = 3420, 3350, 3200, 2950, 2900, 2850, 1725, 1610, 1510, 1460, 1410, 1250, 1130, 1040, 820 'H-NMR (acetone- d 6 ): δ = 1.10 (s, 6H, -CH 3 ), 3.40 (bs, 4H, -NH 2 ), 3.80 (s, 4H, -CH 2 -0-), 2 nd 6.15 ppm (m, 8H, aromatic H) Elemental analysis for C I7 H 22 N 2 : Calculated value (%): C: 73.30, H: 7.91 Measured value (%): C: 73.56, H: 7.78 Example #3 (Sample #1) Preparation of ODPA/Thermid Blend (70/30) To a 1 ,000 ml 4-necked reaction vessel were attached a N 2 inlet and an outlet, and a mechanical stirrer. After the vessel was flushed with N 2 , 38.8631 g (0.125284 mol) of oxydiphthalic acid dianhydride (hereinafter referred to as ODPA) and 15 ml of NMP were added while controlling the temperature of the reaction system to 76+2°C. After confirming that the solution was homogeneous, 50.0 ml (1.26 mol) of dry methanol was added. Oxydiphthalic acid dimethylester was formed by stirring the system at the same temperature for 60 minutes. A solution obtained by dissolving 34.861 g (0.12526 mol) of BAPDMP in 100 ml of dry THF at 76 + 2 °C was added. The mixture was then stirred for 2 hours while maintaining the temperature at 76 + 2 °C. To the reaction mixture was then added a solution prepared by dissolving 25 0 g of "Thermid IP-600" in a mixture of 60 ml of THF and 15 ml of NMP. The resultant system was blended uniformly by stirring it for 2 hours. The viscosity of the mixture after the reaction and blending was measured using a Brookfield Niscometer and found to be 19 poise. Then, the blend mixture was coated on glass cloth (available with a product number "RST57PA-535CS" from Nittobo Co., Ltd.) to impregnate the same by using a prepregger, i.e., a "Model 130 Prepregger" manufactured by Research Tool Co., Ltd. Using the resultant system, a unidirectional reinforced prepreg was produced with two rollers. This reinforced prepreg was cut to a predetermined standard size and then dried under the drying condition shown in Figure 1. 22 prepregs thus obtained, each 102 mm in length and 76 mm in width, were pressed in a stack in precision dies using a press with heater under the condition shown in Figure 2, thus obtaining a heat- resistant laminate material with a thickness of 3.25 mm. Of the heat-resistant laminate material thus obtained, the flexual strength, flexual modulus, G lc (fracture energy) and glass transition temperature (T g ) were measured. The flexual strength and flexual modulus were measured in conformity to ASTM D790M-86. The glass transition point (T g ) was measured using "DMS 200" by Seiko Co., Ltd. and evaluated with the peak value of tan δ. Further, to examine the moisture resistance of the heat-resistant laminate material thus produced, a solder heat resistance test accompanying a pressure cooker test was conducted, and swelling was checked for by appearance observation. Table 1 shows the results of the observations. Example # 4 (Sample #2) Preparation of BT A Thermid Blend (70/30) A blend solution was obtained in the same manner as shown in Example 3 except for using 40.0686 g (0.1248 mol) of benzophenone tetracarboxylic acid dianhydride (hereinafter referred to as BTDA), 34.7545 g (0.1249 mol) of BAPDMP and 19 g of "Thermid IP-600". The resin viscosity of the obtained resin solution was obtained and found to be 21 poise. Using the obtained blend solution, a heat-resistant laminate material with a thickness of 3.42 mm was produced in the manner as shown in Example 3. Of the heat-resistant laminate material thus produced, the various physical property values were measured in the manner as shown in Example 3, and also the moisture resistance was examined. The results of evaluation are shown in Table 1. Example #5 (Sample #3) Preparation of PMDA/BTDA/Thermid Blend (14/56/30) A blend solution was obtained in the manner as shown in Example 3 except for using 9.2031 g (0.0422 mol) of pyromellitic acid dianhydride (hereinafter referred to as PMDA), 20.3560 g (0.06 mol) of BTDA, 29.3297 g (0.10539 mol) of BAPDMP and 20 g of "Thermid IP-600". The resin viscosity of the resin solution thus obtained was measured and found to be 16 poise. Using the blend solution thus obtained, a heat-resistant laminate material with a thickness of 3.42 mm was obtained in the manner as shown in Example 3. Of the heat-resistant laminate material thus produced, the various physical property values were measured in the manner as shown in Example 3, and also the moisture resistance was examined. The results of the evaluation are shown in Table 1. Example #6 (Sample #4) Preparation of PMDA/ODPA Thermid Blend (28/42/30) A blend solution was obtained in the manner as shown in Example 3 except for using 20.8816 g (0.09574 mol) of PMDA, 44.5310 g (0.14356 mol) of ODPA, 66.4659 g (0.23883 mol) of BAPDMP and 57 g of "Thermid IP-600". The resin viscosity of the obtained resin solution was measured and found to be 28 poise. Using the blend solution thus obtained, a heat-resistant laminate material with a thickness of 3.64 mm was produced in the manner as shown in Example 3. Of the heat-resistant laminate material thus produced, the various physical property values were measured, and the moisture resistance was examined. The results of the evaluation are shown in Table 1. Comparative Example #7 (Sample #5) 95 g of "Kerimid 601 " (purchased from Nippon Polyimide Co., Ltd.) was dissolved in 120 g of DMF (resin concentration: 45 wt. %DMF). The resin solution thus obtained was coated on glass fibers to impregnate the cloth in the same manner as shown in Example 1, followed by drying in a hot air circulation furnace at 120°C, or 85 minutes to produce a prepreg with a resin concentration of 40.2% by weight and a residual solvent concentration of 6.4%. Eight prepregs thus formed were laminated at 220°C for 2 hours at 25 kg/cm 2 using a press with heater to obtain a laminate with a thickness of 3.7 mm. Of the heat-resistant laminate material thus produced, the various physical property values were measured in the same manner as in Example 4, and the moisture resistance was examined. The results of this evaluation are shown in Table 1. Comparative Example #8 (Sample #6) 165 g of imide oligomer, i.e., "Thermid MC-600" (purchased from Kanebo NSC Co., Ltd.), was dissolved in 2,000 g of DMF (resin concentration: 45 wt.%). The obtained resin solution was coated on glass fibers to impregnate the same as shown in Example 4, followed by drying in a hot air re-circulation furnace at 120 °C for 35 minutes to obtain a prepreg with a resin concentration of 31.2 % by weight and a residual solvent concentration of 9.4%. Eight prepregs thus obtained were laminated at 220°C for 2 hours at 25 kg/cm 2 to obtain a laminate with a thickness of 6.2 mm. Of the heat-resistant laminate material thus obtained, the various physical property values were measured in the same manner as in Example 4, and the moisture resistance was examined. The results of this evaluation are shown in Table 1. TABLE 1 Ratio of Components Solder Resistance Test 10 Swelling observed after solder bath s (satisfactory) - no swelling observed x (unsatisfactory) - swelling observed PCT (pressure cooker test): swelling observed after 30 second solder bath at 260°C subsequent to treatment at 121°C and under 2 arm. for 5 hours 15 s (satisfactory) - no swelling observed x (unsatisfactory) - swelling observed Example #9 Comparative Sample 1 ' A polyimide preparation by chemical imidization and thermal imidization processes will now be described. Chemical Imidization To a dried 500 ml, 3-necked round bottom flask were attached a bubbler, a N 2 bubbler, and a mechanical stirrer. The flask was flushed with nitrogen and 11.7811 g (42.330 mmol) of BAPDMP dissolved in 100 ml of NMP and 13.1310 g (42.330 mmol) of oxydiphthalic acid dianhydride (hereinafter ODPA) dissolved in 30 ml of N- methyl-2-pyrrolidinone. The solution was dropped into the nitrogen purged reaction vessel at room temperature and allowed to react for 24 hours. A blend solution containing 5 ml (62.00 mmol) of pyridine and 6 ml (62.0 mmol) of acetic anhydride was added and the resultant system allowed to further react for 24 hours. After the reaction, a fiber-like polymer was precipitated in 2,000 ml of ethanol. The polymer was pulverized using a mortar and solvent exchanged for 12-18 hours under reflux using a Soxhlet extractor using methanol as the solvent. The polymer was subsequently dried under reduced pressure at 180°C to obtain 2.4 g (yield 95.8%) of thermoplastic polyimide. The viscosity of the polymer was measured using an Ubbelohde's viscometer (Cannon 200 D481) and found to be η inh = 0.98 dl/g (w-cresol at 30°C, 0.5 g/dl), [η] = 0.83 dl/g (w-cresol, at 30°C). Thermal Imidization To a dried 500 ml 3-necked round-bottomed flask, were attached a bubbler, a N 2 bubbler, a short distillation head with a water trap equipped with a mechanical stirrer. The flask was flushed with nitrogen and 30.5395 g (0.10974 mol) of BAPDMP dissolved in 60 ml of w-cresol and 34.0400 g (0.10974 mol) of ODPA dissolved in 100 ml of w-cresol and added dropwise into the flask with 1 ml of isoquinoline. The reaction was allowed to proceed under nitrogen at room temperature for 2 hours, then heated to 150°C for 2 hours, then allowed to react for an additional 19 hours under imidization conditions After the reaction, a fiber-like polymer was precipitated in 2,000 ml of ethanol. The polymer was pulverized using a mortar and solvent exchanged for 12-18 hours under reflux using a Soxhlet extractor using methanol as the solvent. The polymer was subsequently dried under reduced pressure at 180°C to obtain 59.57 g (yield 98.3%) of thermoplastic polyimide. The viscosity of the polymer was measured using an Ubbelohde's viscometer (Cannon 200 D481) and found to be η inh = 0.88 dl/g (w-cresol at 30°C, 0.5 g/dl), [η] = 0.83 dl/g (w-cresol, at 30°C). Spectral data of the obtained polyimide were as follows. IR (KBr, cm 1 ): v = 3350, 3050, 2950, 1750, 1710, 1505, 1380, 1240, 1170, 1100, 1000, 820 Thermal analysis was conducted using a Seiko TG/DTA200, DSC210 and SCC 5040. The physical properties are summarized in Table 2 (Example 1 '). To determine the mechanical properties, a cast plate was produced under the conditions of 585°F and 3000 psi. All tests were conducted on a cut cast plate with a length of 50.0 mm, 32.0 width, and a thickness of 2.8 mm. Flexural strength and flexural modulus tests were conducted on conformity with ASTM D790M-86 and at 23°C. The fracture energy (G lc ) was measured according with ASTM E399-83. The glass transition point (T g ) was measured using a DMS200 manufactured by Seiko Co., Ltd. using a cast plate with a length of 50 mm, a width of 5 mm and a thickness of 2.5 mm. The evaluation was made with respect to the peak value of tan δ. The glass transition point (T g ) was determined to be 201°C. The data is plotted in Fig. 4. The flexural strength was 30.7 MPa, the flexural modulus was 1.34 GPa, and G lc was 1.35 KJ/m 2 . The results are shown in Comparative Example 1 ' of Table 3. The data of flexural strength, flexural modulus and G lc are plotted in Figs. 5-7 respectively. Example #10 Comparative Sample 2' A polyimide was synthesized according to the steps outlined above for the thermal imidization process in Example #9, except that 18.4707g (66.3697 mol) of BAPDMP, and 21.3845 g (66.3702 mol) of benzophenone tetracarboxylic acid dianhydride (hereinafter BTDA), and 350 ml w-cresol were used thus obtaining 37.2 g (yield 92.3%) of polyimide. Example #11 Comparative Sample 3 ' A polyimide was prepared according to the steps outlined above for the thermal imidization process in Example #9, except that 16.8863 g (60.6766 mol) of BAPDMP, 15.6648 g (48.6182 mol) of BTDA, 2.6508 g of pyromellitic acid dianhydride (hereinafter PMDA), and 300 ml of w-cresol were used thus obtaining 31.0 g (yield 95.6%) of polyimide. Example #12 Comparative Sample 4' A polyimide was prepared according to the steps outlined above for the thermal imidization process in Example #9, except that 16.9641 g (60.9561 mol) of BAPDMP, 5.3232 g (24.4049 mol) of PMDA, 11.3451 g (36.5735 mol) of ODPA and 280 ml of w-cresol were used thus obtaining 31.3 g (yield 92.9%) of polyimide. Example #13 Sample A A blend composition was synthesized by combining thermoplastic polyimide prepared from ODPA and BAPDMP with thermosetting imide oligomer (Thermid IP-600) in a ratio of 4/1. To a dried 500 ml, 3-necked round bottom flask were attached a bubbler, a N 2 bubbler, and a mechanical stirrer. The flask was flushed with nitrogen and 39.3 g of thermoplastic polyimide powder comprising ODPA and BAPDMP, synthesized according to the thermal imidization process detailed in Example #9, and 11.2 g of "Thermid IP-600" (Kanebo NSC) dissolved in 200 ml of w-cresol. The system was stirred at 120°C for 18 hours to obtain a homogeneous solution which was processed according to the procedure outlined for the polymer solution in Example #9, thereby obtaining 28.29 g (yield 55.8%) of the blended powder. Spectral data of the obtained polyimide blend were as follows. IR (KBr, cm 1 ): v = 3350, 2950, 1780, 1710, 1650, 1380, 1240, 1170, 1100, 820 Example #14 Sample B A blend composition was synthesized by charging thermoplastic polyimide, prepared from ODPA and BAPDMP, and thermosetting imide oligomer "Thermid IP- 600" in a ratio of 2/1. Under the same conditions used in Example #13, except for using 9.00 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #9, 4.50 g of "Thermid IP-600" and 300 ml of w-cresol yielded 9.97 g (55.8%) of the blend composition. Example #15 Sample C A blend composition was synthesized by charging thermoplastic polyimide, prepared from ODPA and BAPDMP, and thermosetting imide oligomer "Thermid IP- 600" in a ratio of 1/1. Under the same conditions used in Example #13, except for using 9.16 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #9, 9.12 g of "Thermid IP-600" and 300 ml of w-cresol yielded 7.68 g (99.0%) of the blend composition. Example #16 Sample D A blend composition was synthesized by charging thermoplastic polyimide, prepared from ODPA and BAPDMP, and thermosetting imide oligomer "Thermid IP- 600" in a ratio of 1/2. Under the same conditions used in Example #13, except for using 5.08 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #9, 10.06 g of "Thermid IP-600" and 250 ml of w-cresol yielded 11.3 g (86.9%) of the blend composition. Example #17 Sample E A blend composition was synthesized by charging thermoplastic polyimide, prepared from BDTA and BAPDMP, and thermosetting imide oligomer "^hermid IP- 600" in a ratio of 1/1. Under the same conditions used in Example #13, except for using 8.45 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #10, 8.25 g of "Thermid IP-600" and 200 ml of w-cresol yielded 9.31 g (56.9%) of the blend composition. Example #18 Sample F A blend composition was synthesized by charging thermoplastic polyimide, prepared from BDTA and BAPDMP, and thermosetting imide oligomer "Thermid IP- 600" in a ratio of 2/1. Under the same conditions used in Example 13, except for using 10.45 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #10, 5.05 g of "Thermid IP-600" and 200 ml of w-cresol yielded 7.36 g (56.1%) of the blend composition. Example #19 Sample G A blend composition was synthesized by charging thermoplastic polyimide, prepared from BDTA and BAPDMP, and thermosetting imide oligomer "Thermid IP- 600" in a ratio of 3/1. Under the same conditions used in Example #13, except for using 12.38 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #10, 4.05 g of "Thermid IP-600" and 250 ml of w-cresol yielded 7.50 g (43.9%) of the blend composition. Example #20 Sample H A blend composition was synthesized by charging thermoplastic polyimide, prepared from BDTA and BAPDMP, and thermosetting imide oligomer "Thermid IP- 600" in a ratio of 1/2. Under the same conditions used in Example #13, except for using 5.04 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #10, 10.25 g of "Thermid IP-600" and 200 ml of w-cresol yielded 12.08 g (73.5%) of the blend composition. Example #21 Sample I A blend composition was synthesized by charging thermoplastic polyimide, prepared from BDTA, PMDA and BAPDMP, and thermosetting imide oligomer "Thermid IP-600" in a ratio of 1/1. Under the same conditions used in Example #13, except for using 8.15 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #11, 8.45 g of "Thermid IP-600" and 200 ml of w-cresol yielded 15.12 g (91.1%) of the blend composition. Example #22 Sample J A blend composition was synthesized by charging thermoplastic polyimide, prepared from BDTA, PMDA and BAPDMP, and thermosetting imide oligomer "Thermid IP-600" in a ratio of 1/2. Under the same conditions used in Example #13, except for using 4.45 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #11, 9.67 g of "Thermid IP-600" and 200 ml of w-cresol yielded 12.79 g (90.6%) of the blend composition. Example #23 Sample K A blend composition was synthesized by charging thermoplastic polyimide, prepared from BDTA, PMDA and BAPDMP, and thermosetting imide oligomer "Thermid IP-600" in a ratio of 3/1. Under the same conditions used in Example #13, except for using 9.24 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #11, 3.56 g of "Thermid IP-600" and 250 ml of w-cresol yielded 12.50 g (93.2%) of the blend composition. Example #24 Sample L A blend composition was synthesized by charging thermoplastic polyimide, prepared from ODPA, PMDA and BAPDMP, and thermosetting imide oligomer "Thermid IP-600" in a ratio of 1/1. Under the same conditions used in Example #13, except for using 6.85 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #12, 6.85 g of "Thermid IP-600" and 150 ml of w-cresol yielded 11.04 g (80.9%) of the blend composition. Example #25 Sample M A blend composition was synthesized by charging thermoplastic polyimide, prepared from ODPA, PMDA and BAPDMP, and thermosetting imide oligomer "Thermid IP-600" in a ratio of 1/2. Under the same conditions used in Example #13, except for using 5.06 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Comparative Example 4', 10.01 g of "Thermid IP-600" and 150 ml of w-cresol yielded 10.50 g (69.7%) of the blend composition. Example #26 Sample N A blend composition was synthesized by charging thermoplastic polyimide, prepared from ODPA, PMDA and BAPDMP, and thermosetting imide oligomer "Thermid IP-600" in a ratio of 3/1. Under the same conditions used in Example 1, except for using 18.89 g of thermoplastic polyimide powder synthesized by the thermal imidization process of Example #12, 6.41 g of "Thermid IP-600" and 350 ml of w-cresol yielded 22.26 g (88.0%) of the blend composition. Example #26 Comparative Sample 5' 12.56 g of powdered "Thermid IP-600" was fused in a vacuum oven at 190°C at 3 torr for 2 hours. The solidified resin was powdered, and 8.56 g was used to produce a cast plate under conditions used in Example #9. The physical properties of the samples prepared in Examples 10 through 26 were measured in a manner similar to that described previously in Example 9 and the results summarized in Tables 2 and 3. The thickness of the cast plate produced for the measurements was 3.2 mm, the cast plate having been prepared under the conditions of Fig. 3. The glass transition point, flexural strength, flexural modulus and G lc are plotted in Figs. 4-7. Table 2 10 15 Table 3 10 15 Example #27 Comparative Sample 6 ' The following example illustrates the preparation of a 4:1 blend of a commercial thermoplastic polyimide (Ultem®1000, available from General Electric Plastics) and "Thermid IP-600". 16.0 g of Ultem®1000 was dissolved in 100 ml of DMF by stirring at 140°C for 2 hours under nitrogen, the solution was cooled to 120°C and then 4.0 g of "Thermid IP-600" was added. The mixture was stirred at 120°C for 2 hours to obtain a homogeneous solution. The solution was cooled to 80°C and then added to 800 ml of isopropanol. The blend precipitate that formed was pulverized in a waring blender, washed several times with isopropanol, and dried under reduced pressure at 140°C for 24 hours. The blend powder was compression molded at 280°C under a pressure of 1,000 psi for 20 minutes, the resins underwent considerable flow under these conditions to afford a well consolidated plaque. While in accordance with the patent statutes the best mode and preferred embodiment of the invention have been described, it is to be understood that the invention is not limited thereto, but rather is to be measured by the scope and spirit of the appended claims.

Claims: What is Claimed is: 1. A heat-resistant polyimide blend comprising: (a) a thermoplastic polyimide represented by formula (VI), where Z is a tetravalent organic radical selected from the group consisting of a carbocyclic aromatic containing radical and a heterocyclic aromatic containing radical where each anhydride group is located on an aromatic ring with the carbonyl units in an ortho orientation relative to one another, and where R 1 and R 2 each represent a substituent group selected from the group consisting of hydrogen, aliphatic and aromatic groups from about 1 to 18 carbons, and halogenated aliphatics and aromatics from 1 to 18 carbons, the groups R 1 and R 2 being the same or different, and Ar 1 is a divalent organic aromatic group where the ether linkage and amine linkage are in a para arrangement; and (b) a thermosetting imide oligomer represented by formula (II), wherein Z is as previously defined, the groups Z being either the same or different, and where Q is divalent organic radical selected independently from the group consisting of a carbocyclic aliphatic radical, a carbocyclic aromatic containing radical, and a heterocyclic containing radical, wherein the term carbocyclic aromatic containing radical and heterocyclic aromatic containing radical used to define Z, is meant to include any radical which has the anhydride groups attached to one or more aromatic ring(s) and when describing Q has the amine groups attached to one or more aromatic ring(s), n being a positive integer of from 1 to 30, and X is a form of trivalent bond shown attached to group Z, which occupies two of the bonds, thereby leaving one additional bond for subsequent bonding to other components of the oligomer, and selected from the chemical formula group consisting of (Ilia) (nib) (IIIC) 2. The polyimide blend of Claim 1 which further comprises a reinforcement material selected from the group consisting of woven fabric, non-woven fabric, mat, paper, continuous fiber _. selected from the group consisting of carbon fibers, glass fibers, and aramide fibers, liquid crystal polyester fibers and aluminum fibers. 3. The polyimide blend of Claim 1, wherein a weight ratio of the thermoplastic polyimide represented by formula (NT) to the thermosetting imide oligomer represented by formula (II) is selected in a range of 99/1 to 5/95. 4. The polyimide blend of Claim 1 , wherein the thermoplastic polyimide represented by formula (NI) has a number-average molecular weight of 10,000 or above. 5. A method of manufacturing a heat-resistant polyimide blend comprising: (a) a thermoplastic polyimide represented by formula (NI), where Z is a tetravalent organic radical selected from the group consisting of a carbocyclic aromatic containing radical and a heterocyclic aromatic containing radical where each anhydride group is located on an aromatic ring with the carbonyl units in an ortho orientation relative to one another, and where R 1 and R 2 each represent a substituent group selected from the group consisting of hydrogen, aliphatic and aromatic groups from about 1 to 18 carbons, and halogenated aliphatics and aromatics from 1 to 18 carbons, the groups R 1 and R 2 being the same or different, and Ar 1 a divalent organic aromatic group where the ether linkage and amine linkage are in a para arrangement; and (b) a thermosetting imide oligomer represented by formula (II), where Q is divalent organic radical selected independently from the group consisting of a carbocyclic aliphatic radical, a carbocyclic aromatic containing radical, and a heterocyclic containing radical, wherein the term carbocyclic aromatic containing radical and heterocyclic aromatic containing radical used to define Z, is meant to include any radical which has the anhydride groups attached to one or more aromatic ring(s) and when describing Q has the amine groups attached to one or more aromatic ring(s), n being a positive integer of from 1 to 30, and X is a form of trivalent bond shown attached to group Z, which occupies two of the bonds, thereby leaving one additional bond for subsequent bonding to other components of the oligomer, and selected from the chemical formula group consisting of (Ilia) (IHb) (IIIc) prepared by the steps comprising: (i) dissolving the thermoplastic polyimide of formula (VI) in an organic solvent; (ii) dissolving the thermosetting imide oligomer of formula (II) in an organic solvent; (iii) blending the two solutions to obtain a homogenous blend solution; and (iv) precipitating the blend solution into a coagulating liquid solution. 6. A method of manufacturing a polyimide composition comprising the steps of: (a) dissolving an organic diamine of formula (V) H2N-Q-NH 2 where Q is divalent organic radical selected independently from the group consisting of a carbocyclic aliphatic radical, a carbocyclic aromatic containing radical, and a heterocyclic containing radical, wherein the term carbocyclic aromatic containing radical and heterocyclic aromatic containing radical used to define Q is is meant to have the amine groups attached to one or more aromatic ring(s), and an organic tetracarboxylic acid moiety or derivative thereof of chemical formula represented by formula (IN) where Z is a tetravalent organic radical selected from the group consisting of a carbocyclic aromatic containing radical and a heterocyclic aromatic containing radical where each anhydride group is located on an aromatic ring with the carbonyl units in an ortho orientation relative to one another, wherein the term carbocyclic aromatic containing radical and heterocyclic aromatic containing radical used to define Z, is meant to include any radical which has the anhydride groups attached to one or more aromatic ring(s) in an organic polar solvent to form a polyamic acid solution; (b) imidizing and dehydrating the polyamic acid solution in a non-solvent thereby converting the polyamic acid into a polyimide at a temperature from -50°C to 150°C from 1 to 5 hours; and (c) precipitating the polyimide with a coagulating liquid. 7. The method of Claims 5 or 6 wherein the organic polar solvent is selected from the group consisting of ether solvents, sulfoxide solvents, formamide solvents, phenolic solvents and acetamide solvents or mixtures thereof. 8. The method of Claim 7 wherein the ether solvent is selected from the group consisting of tetrahydrofuran and dioxane, and wherein the sulfoxide solvent is selected from the group consisting of dimethyl sulfoxide and diethyl sulfoxide, and wherein the formamide solvent is selected from the group consisting of Ν,Ν'-dimethylformamide and N,N'-diethylformamide, and wherein the acetamide solvent is selected from the group consisting of N,N'- dimethylacetamide and N,N'-diethylacetamide, and wherein the phenolic solvent is selected from the group consisting of o-cresol, w-cresol, p-cresol and 4-t-butylphenol. 9. The method of Claims 5 or 6 wherein the coagulating liquid solution is a non- solvent selected from the group consisting of alcohols, water, and aralkyl cellosolve or mixtures thereof. 10. The method of Claim 6 wherein the non-solvent is an aromatic hydrocarbon. 11. The method of Claim 10 wherein the non-solvent is selected from the group consisting of xylene and toluene. 12. A method of manufacturing a heat-resistant polyimide blend coated on a reinforcement material comprising the steps of: (a) synthesizing a tetracarboxylic acid compound or derivative thereof represented by formula (VII) CC^Y (Nil) YC^C— z— CC^Y CC^Y where, Y is selected from the group consisting of hydrogen, alkyls from 1 to 5 carbons, the Y groups either being the same or different, and Z is a tetravalent organic group from an alcohol corresponding to a tetracarboxylic acid dianhydride in an inert gas atmosphere and in a temperature range of 50 to 150°C in an organic polar solvent; (b) synthesizing a polyamic acid prepolymer by adding an organic diamine represented by formula (N) H 2 Ν-Q-ΝH 2 where, Q is divalent organic radical selected independently from the group consisting of a carbocyclic aliphatic radical, a carbocyclic aromatic containing radical, and a heterocyclic containing radical, wherein the term carbocyclic aromatic containing radical and heterocyclic aromatic containing radical used to define Q has the amine groups attached to one or more aromatic ring(s); (c) preparing a polymer blend solution by adding a thermosetting imide oligomer represented by formula (II) where Q and Z are as previously defined, n a positive integer of 1 to 30, and X a form of trivalent bond shown attached to group Z, which occupies two of the bonds, thereby leaving one additional bond for subsequent bonding to other components of the oligomer, and selected from a chemical formula group consisting of (Ilia) ( IHb) ( IIIc) (d) coating and impregnating the reinforcement material with the blend polymer solution; and (e) drying the impregnated material to a predetermined residual solvent concentration. 13. The method of Claim 12 wherein the organic solvent is selected from the group consisting of sulfoxide solvents, formamide solvents, acetamide solvents, and pyrrolidinone solvents or mixtures thereof. 14. The method of Claim 13 wherein the sulfoxide solvent is selected from the group consisting of dimethyl sulfoxide, and diethylsulfoxide, and wherein the formamide solvent is selected from the group consisting of N,N'- dimethylformamide and N,N '-diethylformamide, and wherein the acetamide solvent is selected from the group consisting of N,N'-dimethylacetamide and N,N' -diethylacetamide, and wherein the pyrrolidinone solvent is N- methylpyrrolidinone. 15. The method of Claim 12 wherein the aprotic solvent is combined with a non-solvent of polyamic acid. 16. The method of Claim 15 wherein the non-solvent is selected from the group consisting of an alcohol and an aralkyl cellosolve or mixtures thereof. 17. The method of Claim 12 wherein the polyimide blend solution is coated on a reinforcement material selected from the group consisting of woven fabric, non-woven fabric, mat, paper, continuous fibers selected from the group consisting of carbon fibers, glass fibers, and aramide fibers, liquid crystal polyester fibers and aluminum fibers and dried. 18. The method of Claim 12 wherein the concentration of the blend resin in the solvent ranges from 5 to 85 % by weight. 19. The method Claim 18 wherein the residual solvent concentration in the resin blend ranges from 5 to 20 % by weight.

Inventors: FURUTANI HIROYUKI, HARRIS FRANK W, FURUTANI, HIROYUKI, HARRIS, FRANK, W.
Applicants: UNIV AKRON, THE UNIVERSITY OF AKRON
Application year: 1994
Main classification: C08G69
IPC codes: B05D7, C08G73, C08J3, C08J5, C08L79, D06N3, D21H19, H05K1